Stationary riveting machines are well known and widely manufactured. Traditionally, stationary riveting machines include a work table supported on a frame, a riveting plunger or ram supported above the work table, and a riveting stem for setting rivets which is attached to the riveting plunger. The work table is provided with an anvil for upsetting or deforming a rivet after it passes through the registered holes of a work piece. The anvil includes a spring biased pilot pin which is used to register the holes in the work and to guide a rivet through the registered holes. The traditional riveting machine also includes a mechanism commonly known as a "pocket" for transferring a rivet from a rivet feed mechanism to the anvil pilot pin.
A riveting pocket includes a pair of vertically displacable opposing jaws which receive rivets in succession from a rivet feed mechanism. The opposing jaws of a riveting pocket are provided with a vertical bore along their common faces which is sized to accommodate the head of a rivet in an upper region of the bore and the shank of the rivet in a lower region of the bore. Each side of a riveting pocket is attached to a spring-steel pocket arm which permits the opposing jaws of the pocket to be forced apart laterally. The pocket arms are, in turn, connected to a linkage which controls the vertical movement of the pocket.
During each riveting cycle the pocket moves vertically from a rivet receiving position above the work piece to a rivet release position wherein the hollow lower end of the rivet shank has engaged the tip of the pilot pin. Most stationary riveting machines control the vertical movement of the pocket with a spring or cam biased linkage that is attached to the top of the pocket arms. The linkage is adjusted to stop the descent of the pocket when the transferring a rivet from a rivet feed mechanism to the anvil pilot pin.
A riveting pocket includes a pair of vertically displaceable opposing jaws which receive rivets in succession from a rivet feed mechanism. The opposing jaws of a riveting pocket are provided with a vertical bore along their common faces which is sized to accomodate the head of a rivet in an upper region of the bore and the shank of the rivet in a lower region of the bore. Each side of a riveting pocket is attached to a spring-steel pocket arm which permits the opposing jaws of the pocket to be forced apart laterally. The pocket arms are, in turn, connected to a linkage which controls the vertical movement of the pocket.
During each riveting cycle the pocket moves vertically from a rivet receiving position above the work piece to a rivet release position wherein the hollow lower end of the rivet shank has engaged the tip of the pilot pin. Most stationary riveting machines control the vertical movement of the pocket with a spring or cam biased linkage that is attached to the top of the pocket arms. The linkage is adjusted to stop the descent of the pocket when the rivet shank engages the top of the pilot pin. When the pocket is stopped in its downward descent, the opposing jaws of the pocket are forced apart by the descending force of the stem and the rivet follows the pilot pin down through the registered holes of the work pieces and is upset against the anvil on the back side of the work.
The disadvantage of the known stationary riveting machines is the fact that the riveting pocket prevents the setting of rivets in certain areas of a work piece. For instance, using a traditionally equipped riveting machine, one cannot readily set a rivet adjacent a 90.degree. angle, in the bottom of a narrow cylinder, or in any other location where a rivet is desirably set in a portion of the work adjacent some obstruction or protrusion. This problem often requires the use of more expensive and less desirable "pop" rivets or some alternate fastener where an upset rivet cannot be set. In certain applications, the size of a pocket is sometimes reduced to improve the versatility of the machine. Elongated pilot pins which project far enough above the work to guide a rivet past a projecting surface of the work have also been used for setting rivets in certain applications. Neither of these adaptions have proven practical for all applications. Regardless of how thinly the walls of a pocket are made, the pocket still requires considerable operating space, rendering it unsuitable for certain riveting applications. Although an elongated pilot pin may be useful in certain situations where only a few rivets must be set, it is an unsatisfactory method for setting a large number of rivets. There are several disadvantages to working with an elongated pilot pin. Firstly, the pin requires a very long and resilient spring which tends to fatique and wear quickly. Secondly, the extra long projection of the pilot pin provides less clearance between the bottom of a pocket and the top of the pin, which may interfere with the movement of work pieces over the pilot pin. In addition, attempts to match a hole with a very long pilot pin may result in damaging the pilot pin by bending or breaking it and thus rendering it unsuitable for further use.
It is an object of the present invention to provide a riveting stem and a pocket for a stationary riveting machine which is reliably capable of setting ferrous rivets in practically any area of a work piece, including areas adjacent projecting surfaces, inside corners, and within narrow recesses.
It is a further object of the invention to provide a riveting stem and pocket for a stationary riveting machine which are simple to manufacture, operate and maintain.